A variety of organosilicon polymers are known in the art. For instance, BALDWIN et al., U.S. Pat. No. 4,581,391, discloses, as high temperature insulating materials, high viscosity linear siloxane polymers, characterized by high molar percentages of the vinylmethylsiloxane unit; the increased crosslink density of such polymers increases their char yield.
Also known in the art are organosilicon polymers characterized by alternating compound residues, at least one such residue being the residue of a silicon compound. For instance, LEIBFRIED '779, U.S. Pat. No. 4,900,779, and LEIBFRIED '731, U.S. Pat. No. 4,902,731, disclose alternating polycyclic polyene residues and cyclic polysiloxane or tetrahedral siloxysilane residues; LAMOREAUX '432, U.S. Pat. No. 3,197,432, discloses alternating cyclic polysiloxane residues and olefinic tetramer cyclic polysiloxane (for instance, tetravinyltetramethylcyclotetrasiloxane, hereinafter referred to as TVTMS) residues; and LAMOREAUX '433, U.S. Pat. No. 3,197,433, and LAMOREAUX '936, U.S. Pat. No. 3,438,936 also disclose vinyl bearing cyclic siloxanes.
There is no disclosure or suggestion in the art of organosilicon polymers comprising polycyclic polyene, and both:
cyclic polysiloxane and/or tetrahedral siloxysilane; and PA1 at least one silicon compound comprising two or more silicon atoms, each having an olefinically unsaturated hydrocarbyl group attached thereto (e.g., TVTMS). Further, it has been found that such polymers, of the instant invention, have advantages over the polymers previously known in the art --notably those of LEIBFRIED and LAMOREAUX. PA1 terminally monoolefinic aliphatic groups, preferably having ten or fewer carbon atoms, and most preferably four or fewer carbon atoms; PA1 aliphatic groups having at least one nonterminal carbon-carbon double bond, preferably having one carbon-carbon double bond and ten or fewer, most preferably four or fewer, carbon atoms; PA1 alkyl groups; PA1 cycloalkyl groups; PA1 aromatic groups; PA1 aralkyl groups; and PA1 alkaryl groups. PA1 R' and R" may be the same or different, each, or at least substantially each, being a hydrocarbyl group containing at least one carbon-carbon double bond; and PA1 n' is an integer of from 3 to about 20. PA1 n' is 3 or 4, most preferably 3; PA1 each R is the same, and is selected from the group consisting of methyl and phenyl, most preferably methyl; and PA1 R' and R" are the same, and are selected from the group consisting of vinyl and allyl, and are preferably vinyl.
As to the former, the final polymer products of LEIBFRIED '779 and LEIBFRIED '731 are prepared, as disclosed therein, from prepolymers obtained by reacting polycyclic polyenes with cyclic polysiloxanes or tetrahedral siloxysilanes. These prepolymers are characterized by a viscosity in the range of 4-100 stokes, at 25.degree. C., which is high enough to be disadvantageous in certain applications.
For instance, the LEIBFRIED prepolymers can be combined with reinforcements and fillers, for molding into useful composite parts. Although these prepolymers have sufficient fluidity so that they can be processed to obtain reinforced composite parts, because of the degree of their viscosity, heating must often be used to promote flow, penetration, and wetting of the reinforcement.
Further heating can decrease the working time of the prepolymer in molding, composite lay ups, or filament winding. Accordingly, the viscosity of these prepolymers puts an upper limit on the amount of particulate filler which can be used in any application.
In contrast, combination of the previously discussed at least one further silicon compound with the prepolymer, in accordance with the instant invention, significantly decreases formulation viscosity. Moreover, the presence of this at least one further silicon compound also provides higher thermogravimetric analysis (TGA) residues with regard to the final polymer product.
As to the LAMOREAUX-type alternating residue polymers, these, upon curing, are extremely brittle, breaking during the Rheometrics Dynamic Spectrometer (RDS) mechanical test; the modulus (G') is in the 8-9.times.10.sup.9 dynes/cm.sup.2 range (0.8 GP.sub.a) Phenyl silanes are added to decrease the brittleness of these polymers.
The polymers of the invention are not characterized by such brittleness, and therefore do not require such phenyl silane additives.
The polymers of the invention further have many useful characteristics, and can be employed in a variety of applications. These are discussed subsequently herein in detail.